Simultaneous forward and backward terahertz generations in periodically poled stoichiometric LiTaO3 crystal using femtosecond pulses

Forward and counterpropagated backward terahertz generations were demonstrated via difference frequency generation using a femtosecond laser. By cooling the crystal to reduce terahertz losses, we achieved the terahertz generations of 1.36 and 0.65THz. Temperature-dependent measurements showed gradual intensity increase of the terahertz pulse and red shift of the center frequency as the temperature decrease from 255to143K, although there were insignificant decreases of the spectral bandwidth.